Bolt action muzzle loading firearm

ABSTRACT

A muzzle loading firearm includes a barrel, a receiver, and a breech plug located at the breech end of the barrel. An insert integral with or attached to the breech plug provides sealing engagement against an opening in a cartridge case. The breech plug and insert together define a bore to allow a flame from an ignited primer on a cartridge casing to travel to a projectile propellant at the breech end of the barrel. A bolt without conventional lugs is movable within the receiver between an open position and a closed position. A pin extends through the receiver engaging a camming groove in the bolt to guide and lock the bolt against a primer end of an ignition casing. The camming groove and metal pin are configured to compress a face of the ignition cartridge against the breech plug when the bolt is in the closed position.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

FIELD OF THE INVENTION

This disclosure relates to bolt action muzzle loading firearms.

BACKGROUND OF THE INVENTION

Muzzle loading firearms, in which the projectile and the propellantcharge are loaded from the muzzle end of the barrel, have becomeincreasingly popular due in part to the establishment of special muzzleloader only seasons in many states.

In-line bolt action muzzle loading firearms are particularly popularwith hunters and firearms enthusiasts that prefer a modernconfiguration. A significant example of such firearms is disclosed in myprior U.S. Pat. Nos. 5,706,598 and 6,385,887, which are herebyincorporated by reference in their entireties herein. These patentsdescribe an adaptor or breech plug for mounting a cartridge casing thatis used to convert a standard cartridge firing firearm into a muzzleloading firearm. A cartridge case with a primer, but without a bullet orpropellant, is placed into the breech and the bolt closed to lock thecartridge into place. In each of my patents, it is described that thebolt is provided with camming lugs on the bolt adjacent the breech endto lock the bolt in the receiver. In order to accommodate the camminglugs at the breech end of the bolt, the receiver must have channels orraceways configured for receiving the camming lugs. Considerablemachining is required to provide the raceways or channels for camminglocks. A problem is that it is possible to convert the firearm to be amodern breech loading firearm by replacing the barrel. The presentinvention prevents this possibility.

Various other inserts and adapters with a nipple have been used toconvert a cartridge gun into a black powder muzzle loading firearm usinga percussion primer cup. The cap is small and difficult to place on thenipple, and various muzzle loading firearms that do not use a primedcartridge casing for igniting the projectile propellant are described inthe literature.

SUMMARY OF THE DISCLOSURE

Disclosed is a muzzle loading, bolt action firearm with a receiver and abarrel into which a propellant and bullet is introduced through themuzzle, which comprises: (a) a bolt assembly with a cylindrical boltbody defining a longitudinal axis, with a cross-sectional diameter alongthe axis from a distal end to a proximal end, with a face at theproximal end adapted for engaging a head of a primed cartridge casing,and a longitudinal slot along a surface of the body adapted to engage aguide pin on the receiver, and with a spring loaded firing pin adaptedto selectively engage the primer on the cartridge casing when releasedby a sear activated by a trigger on the firearm; (b) a handle mounted onthe bolt body adapted to longitudinally slide the body along a matingcylindrical opening in the receiver, wherein the slot with the guide pinis adapted to guide the bolt body in the receiver to move the bolt alongthe axis until the face engages the head of the cartridge casing, androtate the body on the axis into a locked position in the receiver, andwherein when the bolt body is rotated by the arm in the receiver, thebolt face is configured to press an inside of the casing opposite theprimer against a member with an opening into the barrel for igniting thepropellant. In certain embodiments, the slot is rectangular incross-section. In certain embodiments, the slot is angled adjacent thehandle towards the face of the bolt and the pin on the receiver ispositioned to mate with the slot. In certain embodiments, the bolt hasan area of milled off lugs adjacent the face of the bolt. In certainembodiments, the bolt has a substantially constant cross-sectional shapeat an area adjacent the face of the bolt. In certain embodiments, thepin is hardened steel.

Further, disclosed is a bolt and receiver assembly adapted for a muzzleloading, bolt action firearm with a barrel mounted on the receiver intowhich a propellant and bullet is introduced through the muzzle, whichcomprises: (a) a bolt assembly with a cylindrical bolt body defining alongitudinal axis, with a cross-sectional diameter along the axis from adistal end to a proximal end, with a face at the proximal end adaptedfor engaging a head of a primed cartridge casing, with a longitudinalslot along a surface of the body adapted to engage a guide pin on thereceiver, and with a spring loaded firing pin adapted to selectivelyengage the primer on the cartridge casing when released by a searactivated by a trigger on the firearm; (b) a handle mounted on the boltbody adapted to longitudinally slide the body along a mating cylindricalopening in the receiver, wherein the slot with the guide pin is adaptedto guide the bolt body in the receiver to move the bolt along the axisuntil the face engages the head of the cartridge casing and rotate thebody on the axis into a locked position in the receiver, and whereinwhen the bolt body is rotated by the arm in the receiver, the bolt faceis configured to press an inside of the casing opposite the primeragainst a member with an opening into the barrel for igniting thepropellant. In certain embodiments, the slot is rectangular incross-section. In certain embodiments, the slot is angled adjacent thehandle towards the face of the bolt and the pin on the receiver ispositioned to mate with the slot. In certain embodiments, the bolt hasan area of milled off lugs adjacent the face of the bolt. In certainembodiments, the bolt has a substantially constant cross-sectional shapeat an area adjacent the face of the bolt. In certain embodiments, thepin is hardened steel.

Further still, disclosed is a bolt assembly adapted for a muzzleloading, bolt action firearm with a receiver and a barrel into which apropellant and bullet is introduced through the muzzle, which comprises:(a) a cylindrical bolt body defining a longitudinal axis, with across-sectional diameter along the axis from a distal end to a proximalend, with a face at the proximal end adapted for engaging a head of aprimed cartridge casing, with a longitudinal slot along a surface of thebody adapted to engage a guide pin on the receiver, and with a springloaded firing pin adapted to selectively engage the primer on thecartridge casing when released by a sear activated by a trigger on thefirearm; (b) a handle mounted on the bolt body adapted to longitudinallyslide the body along a mating cylindrical opening in the receiver,wherein the slot with the guide pin is adapted to guide the bolt body inthe receiver to move the bolt along the axis until the face engages thehead of the cartridge casing and to rotate the body on the axis into alocked position in the receiver, and wherein when the bolt body isrotated by the arm in the receiver the bolt face is configured to pressan inside of the casing opposite the primer against a member with anopening into the barrel for igniting the propellant. In certainembodiments, the slot is rectangular in cross-section. In certainembodiments, the slot is angled adjacent the handle towards the face ofthe bolt and the pin on the receiver is positioned to mate with theslot. In certain embodiments, the bolt has an area of milled off lugsadjacent the face of the bolt. In certain embodiments, the bolt has asubstantially constant cross-sectional shape at an area adjacent theface of the bolt.

Finally, disclosed is a muzzle loading bolt action firearm having afiring pin mechanism, comprising: a barrel having a breech end and acenter bore along a longitudinal axis; a receiver mounted on the breechend of the barrel; a breech plug with an orifice along the axis locatedat the breech end of the barrel with an opening for a cartridge casing;an insert integral with or attached to the breech plug for sealinglyengaging against a primer opening inside a cartridge case, the breechplug and the insert together defining a bore to allow a flame from anignited primer to travel to a projectile propellant at the breech end ofthe barrel, and to provide a seal between the receiver and the barrel; asubstantially cylindrical bolt aligned with the longitudinal axiswithout radially projecting the lug that is recipricatable and partiallyrotatable within the receiver between an open position in which thebreech end of the barrel is accessible for loading or removing thecartridge casing and a closed position in which an end of the bolt cancompressibly engage against the casing adjacent the primer cartridge,the bolt having a camming groove with a first section that extendslongitudinally parallel to the axis and a second section that extends atan angle from a rearward end of the first section; and a pin thatextends through a wall of the receiver and engages the camming groove toguide the bolt and lock the bolt against the primer at the face end ofthe ignition casing when it is loaded into the receiver, the camminggroove and the metal pin configure to compress the face end of theignition casing against the breech plug when the bolt is rotated intothe closed position. In certain embodiments, the pin is threaded tofacilitate removal of the pin from the receiver and for removal of thebolt from the receiver. In certain embodiments, the breech plug includesexternal threads and the breech end of the barrel includes internalthreads engagable with the external threads of the breech plug.

Disclosed is a bolt and receiver dedicated muzzle loading, bolt actionfirearm that utilizes a modern configuration.

The muzzle loading firearm can employ a greatly modified cartridge boltreceiver without locking lugs that would normally project radially fromthe bolt adjacent the breech or forward end of the bolt, and a bolt thatdoes not have locking lugs projecting from the forward end of the bolt.The absence of locking lugs and preferably raceways for the locking lugsprevents the firearm from being easily converted from a muzzle loadingfirearm into a center fire firearm. Without locking lugs on the bolt,and channels in the receiver for receiving the locking lugs, the boltwould not have sufficient locking strength to withstand the pressurefrom a modern cartridge. In a muzzle loading firearm, the pressuregenerated by the projectile propellant during firing is kept forward ofthe barrel breech by the breech plug, and thus locking lugs are notrequired. It would require a new bolt with locking lugs and a receiverwith raceways to convert the muzzle loading firearm into a center firefirearm.

In certain embodiments, the muzzle loading firearm has a barrel having abreech end and a center bore, a receiver at the breech end of thebarrel, and a breech plug located at the breech end of the barrel. Aninsert integral with or attached to the breech plug is provided forsealingly engaging against a primer opening in a cartridge case. Thebreech plug and insert together define a bore that allows a flame froman ignited primer inside the cartridge case to travel through the insertto a projectile propellant located at the breech end of the barrelforward of the breech plug. The breech plug and insert together alsoprovide a seal for the barrel with the cartridge case.

The bolt that is substantially cylindrical without radially projectinglugs is recipricatable and partially rotatable within the receiverbetween an open position in which the breech end of the barrel isaccessible for loading or removing the cartridge casing and a closedposition in which an end of the bolt can compressibly engage against aprimed cartridge case. The bolt includes a groove with a first sectionthat extends longitudinally along the longitudinal axis and a secondsection that extends arcuately at an angle from a rearward end of thefirst section as a continuous channel. A pin extends through a wall ofthe receiver and engages the groove to move the bolt and lock the boltto be compressed against a primer end of the ignition casing when thecasing is loaded into the receiver. The ramming groove and metal pin areconfigured to compress a face end of the ignition cartridge casingagainst the insert inside face of a cartridge case when the bolt isrotated into the closed position.

The pin can be threaded to facilitate removal of the pin and the boltfrom the receiver. The diameter of the bore extending through the insertcan be substantially the same as a diameter of an opening in a head of acartridge casing adjacent a primer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a barrel and action for the muzzle loadingfirearm with a longitudinal axis A-A.

FIG. 1A is an elevational view of the breech end of the cartridge shownin FIG. 1.

FIG. 1B is a cross-sectional view of the cartridge shown in FIG. 1.

FIG. 2 is a vertical cross-sectional view of the barrel and part of theaction shown in FIG. 1.

FIG. 3 is a perspective view of the new bolt used in the receiver.

FIG. 3A is a cross-sectional view of the bolt shown in FIG. 3.

FIG. 4 is a perspective view of the barrel and action shown in FIG. 1.

FIG. 5 is a vertical cross-sectional view of the barrel and part of thebolt and receiver action shown in FIG. 1, with the bolt in the closedposition, ready for firing.

FIG. 6 is a vertical cross-sectional view of the barrel and action shownin FIG. 1, with the bolt in the closed position and the firing pinengaged with a primer in the cartridge casing to ignite the powder inthe barrel.

FIG. 7 is a perspective view of a breech plug and insert mounted in thebreech end of the barrel.

FIG. 8 is a side view of the barrel and the breech plug illustrating howthe breech plug is installed in the barrel.

FIG. 9 is an end view as seen along view lines B-B of FIG. 8.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

A barrel 10 having center bore 11 along axis A-A and action 12 for themuzzle loading firearm is shown in FIGS. 1 and 2. Firing action 12includes barrel 10, a receiver 18, a trigger mechanism 14, a bolt action15 and safety 14A. The trigger mechanism 14, safety 14A and barrel 10may be of any suitable design, examples of which are commerciallyavailable. Bolt 15 carrying a firing pin mechanism 50 is mounted inreceiver 18 for reciprocating movement in a direction substantiallyaligned with the longitudinal axis A-A of barrel 10. Firing pin 50 canbe generally any suitable design, such as those customarily employed incenter fire rifles. Bolt 15 functions to lock a cartridge casing 19 inposition against an insert 34 (shown in FIG. 2). Mounted generallybetween barrel 10 and receiver 18 is a recoil lug 20 for transferringrecoil from the action to the stock (not shown).

As illustrated in FIGS. 3 and 4, bolt 15 is removably retained andguided in receiver 18 by a guide pin 22 (e.g., a removable threadedscrew which is hardened to the same standards as the receiver 18) thatengages a camming groove 24. Guide pin 22 can, for example, have ahexagonal recess 22A for receiving a tool (e.g., an Allen wrench).Groove 24 includes a first section 25 that extends longitudinally alongbolt 15 and a second section 26 that extends at a radial angle from therearward end of the first section 25 of the groove 24 in a directionthat is generally opposite to the direction that handle 46 extends frombolt 15 (see FIGS. 3 and 4). The angle and radius of the curvedtransition 30 from the first section 25 of the groove 24 to the secondsection 26 of groove 24 are configured with pin 22 to compress acartridge case head 32 (FIG. 5) between a forward face or front end 15Aof bolt 15 and an insert 34 mounted in a center bore 36 (see FIG. 7) ofbreech plug 16. Removal of bolt 15 from receiver 18 by removing guidepin 22 facilitates cleaning of the bolt 15 and receiver 18.

As shown in FIG. 8, breech plug 16 has external threads 38 to facilitateengagement with internal threads 40 inside barrel 10 (see FIG. 2) andallow breech plug 16 to be sealingly engaged with barrel 10 in use andremovable as desired for cleaning or unplugging barrel 10. Externalbarrel threads 45 are used to mount barrel 10 onto receiver 18 withrecoil lug 20 disposed in a groove defined between barrel 10 andreceiver 18. In addition to transferring recoil to the stock, recoil lug20 can include means for positioning the firing action 12 on a gun stock(not shown) and/or securing the firing action 12 to a gun stock. Breechplug 16 includes an insert 34 having walls 42 defining a hexagonalcross-section that can be engaged by a socket wrench to facilitateinstallation of breech plug 16 into barrel 10 and removal of breech plug16 from barrel 10 as needed or desired. Other configurations and toolsmay be used as desired.

As shown in FIG. 3, bolt 15 is substantially cylindrical in shape andhas a substantially constant cross-sectional shape along its length,including an area adjacent the face of the bolt (forward end), deviatingsignificantly only adjacent the cocking extension 44 where bolt handle46 projects laterally. Because bolt 15 does not have locking lugs or anyother features projecting radially adjacent to forward end 15A of bolt15, receiver 18 preferably does not need raceways for receiving lugsthat would normally project from the bolt 15 of a center fire rifle.

As can be seen in FIGS. 5 and 6, in the firing position, the rearwardend 34A of insert 34 is sealingly pressed up against a center opening inhead 32 of cartridge casing 19 so that upon actuating trigger mechanism14, firing pin 50 is released from the position shown in FIG. 5 andforcefully impacts a primer 52 held in an opening 19A at the head 32 ofcartridge 19, causing a flame or spark to rapidly travel through anarrow bore 54 extending through insert 34 to projectile propellant 56,igniting propellant 56 and causing explosive combustion of thepropellant 56 and a rapid generation of high pressure gases which propelprojectile 58 from the muzzle of barrel 10. In the illustratedembodiment, shown in FIGS. 2, 5 and 6, three black powder propellantpellets 56 are shown for propelling a conical bullet projectile 58.Loose powder can also be packed into the breech of the barrel with aramrod as described in my U.S. Pat. No. 5,706,598. Each of theillustrated propellant pellets 56 includes a center bore 62 thatprovides an extended passageway for a flame or spark travelling throughbore 54 of insert 34 to continue rapidly travelling through propellants56, allowing substantially simultaneous explosive combustion of allpropellants 56, and rapid development of very high pressures to allowdevelopment of higher projectile velocities upon firing than what couldotherwise be achieved, such as with packed black powder. However, othertypes of propellants, amounts of propellant, and types of projectiles,such as patched round balls, may be used. In the illustrated embodimentshown in FIGS. 5 and 6, the projectile is saboted. Sabot 60 can beself-lubricating to facilitate loading of projectile 58.

Insert 34 can be integral with breech plug 16 (e.g., permanentlyaffixed), or insert 34 can be removably attached to breech plug 16, suchas with interlocking threads.

Referring to FIGS. 1 and 2, in use, the propellant 56 is loaded into thebarrel 10 adjacent to the insert 34 using a ramrod (not shown). Then thecartridge casing 19 is inserted adjacent the insert 34, and bolt 15 isslid in receiver 18 so that forward face 15A engages the casing 19 andpushes it onto the insert 34 so that face 15A of the bolt 15 presses theopening 19A against the rearward end 34A of insert 34. The movement ofthe bolt 15 locks the firing pin 50 back, compressing spring 50A into aposition in which the firearm is ready to be fired. Trigger 14B issqueezed so that the firing pin 50 slides down and impacts primer 52igniting the propellant 56 in the barrel 10 and driving projectile(e.g., bullet) 58 out of the barrel 10.

While the illustrated embodiment is in a rifle or long gun format, theprinciples and physical structures described herein are adaptable tovarious other firearms, including pistols.

The various components of the muzzle loading firearm can be fabricatedfrom any suitable steels, such as those materials that areconventionally employed in the manufacture of rifles. However, becausebreech plug 16 isolates receiver 18 from the high pressures developed inbarrel 10 during firing of the firearm, cartridge casing 19 need notnecessarily be made of brass, but instead could be made of a plasticmaterial (a thermoplastic or thermoset polymeric material), a ceramicmaterial, other metals (such as steel or aluminum), or other materials.Additionally, because the cartridge casing does not need to expand andseal against the walls of the receiver during firing, cartridge 19 canhave a shape that is not necessarily cylindrical.

The design of the firing action 12 facilitates production of anextremely safe muzzle loading, bolt action firearm employing a primedcartridge casing 19 to ignite a propellant 56 and discharge a projectile58 from the muzzle end of barrel 10. The design includes a bolt 15, acartridge chamber defined in a portion of receiver 18, a breech plug 16and insert 34 that cooperatively function to hold primed cartridgecasing 19 in a protected area wherein the extremely high gas pressuresthat can be developed during explosive combustion of propellant 56 aresafely contained and directed substantially entirely through the muzzleend of barrel 10 by compressing cartridge casing 19 between forward face15A of bolt 15 and rearward or breech end 34A of insert 34. Unlike aconventional bolt action firearm using a primed cartridge to ignite thepropellant, whether a muzzle loading firearm or a center loadingfirearm, wherein the bolt has a longitudinal slot that is used primarilyfor guiding the bolt within the receiver and locking lugs are used forlocking the cartridge in a cartridge chamber of the receiver, the novelfirearm disclosed herein eliminates the conventional locking lugs usedwith primed cartridges and instead employs a groove 24 on bolt 15, whichin combination with guide pin 22 serves both the guiding function of aconventional longitudinal bolt slot, while also functioning to lock theprimed cartridge casing in a cartridge chamber of the receiver so thatthe cartridge casing is securely compressed between a forward end orface 15A of bolt 15 and a rearward end 34A of insert 34. The lockingaction is achieved without locking lugs by employing very precisedimensional tolerances in the various components, and in particular bolt15 has a groove 24 with a transition portion 30 that is preciselydesigned to employ a camming action with pin 22 to securely lock primedcartridge casing 19 in a proper position for firing. Additionally,breech plug 16 and insert 34 are designed to direct a flame or sparkfrom the primer in the cartridge through a narrow bore 54 that allowsthe flame or spark to ignite propellant 56, but which is sufficientlynarrow to restrict the development of high back pressures in receiver18. This combination of features makes it possible to employ a primedcartridge casing for igniting a propellant and discharging a projectilefrom a muzzle loading firearm without requiring locking lugs and,therefore, without requiring raceways machined into the receiver for thelocking lugs. By eliminating the locking lugs and raceways for the lugs,that are conventionally employed for bolt action firearms using a primedcartridge to ignite the projectile propellant, it becomes impracticaland nearly impossible to convert the firearm for use as a centerfirerifle, as this would require, at minimum, removal of breech plug 16 andinsert 34 from barrel 10, replacement of bolt 15 with a bolt havinglocking lugs that are needed to contain the high back pressure developedin a receiver when the breech end of the barrel is open, and substantialmachining of the receiver to provide raceways for the locking lugs.

In addition to providing a muzzle loading, bolt action firearm that isextremely safe to use, while facilitating very high projectilevelocities and accurate shooting, and preventing easy modification foruse as a centerfire rifle, the disclosed firearm can be configured asillustrated to facilitate easy disassembly and reassembly for cleaningand/or to remove blockages in the field, at a remote location, such asduring hunting, using only easily portable hand tools, such as an Allenwrench to remove pin 22 and bolt 15, and a socket wrench to removeand/or install breech plug 16 and insert 34.

This combination of convenience, safety and dedication to muzzleloading, rather than convertibility to center loading, was notpreviously known or imagined, thereby providing a unique firearm withsignificant advantages over previously known muzzle loading firearms,including those disclosed in my previous patents.

Many modifications and variations of the present disclosure are possiblein light of the above teachings. Therefore, within the scope of theappended claims, the present disclosure may be practiced other than asspecifically described.

What is claimed:
 1. A muzzle loading, bolt action firearm with areceiver and a barrel into which a propellant and bullet is introducedthrough the muzzle, which comprises: (a) a bolt assembly with acylindrical bolt body defining a longitudinal axis, with across-sectional diameter along the axis from a distal end to a proximalend, with a face at the proximal end adapted for engaging a head of aprimed cartridge case, with a longitudinal slot along a surface of thebody adapted to engage a guide pin on the receiver, and with a springloaded firing pin adapted to selectively engage the primer on thecartridge casing when released by a sear activated by a trigger on thefirearm; and (b) a handle mounted on the bolt body adapted tolongitudinally slide the body along a mating cylindrical opening in thereceiver, wherein the slot with the guide pin is adapted to guide thebolt body in the receiver to move the bolt along the axis until the faceengages the head of the cartridge casing and to rotate the body on theaxis into a locked position in the receiver, and wherein when the boltbody is rotated by the arm in the receiver the bolt face is configuredto press an inside of the casing opposite the primer against a memberwith an opening into the barrel for igniting the propellant.
 2. Thefirearm of claim 1 wherein the slot is rectangular in cross-section. 3.The firearm of claim 1 wherein the slot is angled adjacent the handletowards the face of the bolt and the pin on the receiver is positionedto mate with the slot.
 4. The firearm of claim 1 wherein the bolt has asubstantially constant cross-sectional shape at different locationsalong the length of the bolt at a section adjacent the face of the bolt.5. The firearm of claim 1 wherein the bolt has an area of milled offlugs adjacent the face of the bolt.
 6. The firearm of claim 1 whereinthe pin is hardened steel.
 7. A bolt and receiver assembly adapted for amuzzle loading, bolt action firearm with a barrel mounted on thereceiver into which a propellant and bullet is introduced through themuzzle, which comprises: (a) a bolt assembly with a cylindrical boltbody defining a longitudinal axis, with a cross-sectional diameter alongthe axis from a distal end to a proximal end, with a face at theproximal end adapted for engaging a head of a primed cartridge casing,with a longitudinal slot along a surface of the body adapted to engage aguide pin on the receiver, and with a spring loaded firing pin adaptedto selectively engage the primer on the cartridge casing when releasedby a sear activated by a trigger on the firearm; and (b) a handlemounted on the bolt body adapted to longitudinally slide the body alonga mating cylindrical opening in the receiver, wherein the slot with theguide pin is adapted to guide the bolt body in the receiver to move thebolt along the axis until the face engages the head of the cartridgecasing and to rotate the body on the axis into a locked position in thereceiver and wherein when the bolt body is rotated by the arm in thereceiver the bolt face is configured to press an inside of the casingopposite the primer against a member with an opening into the barrel forigniting the propellant.
 8. The bolt and receiver assembly of claim 7wherein the slot is rectangular in cross-section.
 9. The bolt andreceiver assembly of claim 7 wherein the slot is angled adjacent thehandle towards the face of the bolt and the pin on the receiver ispositioned to mate with the slot.
 10. The bolt and receiver assembly ofclaim 7 wherein the bolt has a substantially constant cross-sectionalshape at different locations along the length of the bolt at a sectionadjacent the face of the bolt.
 11. The bolt and receiver assembly ofclaim 7, wherein the bolt has an area of milled off lugs adjacent theface of the bolt.
 12. The bolt and receiver assembly of claim 7 whereinthe pin is hardened steel.
 13. A bolt assembly adapted for a muzzleloading, bolt action firearm with a receiver and a barrel into which apropellant and bullet is introduced through the muzzle, which comprises:(a) a cylindrical bolt body defining a longitudinal axis, with across-sectional diameter along the axis from a distal end to a proximalend, with a face at the proximal end adapted for engaging a head of aprimed cartridge casing, with a longitudinal slot along a surface of thebody adapted to engage a guide pin on the receiver, and with a springloaded firing pin adapted to selectively engage the primer on thecartridge casing when released by a sear activated by a trigger on thefirearm; and (b) a handle mounted on the bolt body adapted tolongitudinally slide the body along a mating cylindrical opening in thereceiver, wherein the slot with the guide pin is adapted to guide thebolt body in the receiver to move the bolt along the axis until the faceengages the head of the cartridge casing and to rotate the body on theaxis into a locked position in the receiver, and wherein when the boltbody is rotated by the arm in the receiver the bolt face is configuredto press an inside of the casing opposite the primer against a memberwith an opening into the barrel for igniting the propellant.
 14. Thebolt assembly of claim 13 wherein the slot is rectangular incross-section.
 15. The bolt assembly of claim 13 wherein the slot isangled adjacent the handle towards the face of the bolt and the pin onthe receiver is positioned to mate with the slot.
 16. The bolt assemblyof claim 13 wherein the bolt has a substantially constantcross-sectional shape at different locations along the length of thebolt at a section adjacent the face of the bolt.
 17. The bolt assemblyof claim 13 wherein the bolt has an area of milled off lugs adjacent theface of the bolt.
 18. The bolt assembly of claim 13 wherein the pin ishardened steel.
 19. A muzzle loading, bolt action firearm having afiring pin mechanism, comprising: a barrel having a breech end and acenter bore along a longitudinal axis; a receiver mounted on the breechend of the barrel; a breech plug with an orifice along the axis locatedat the breech end of the barrel with an opening for a cartridge casing;an insert integral with or attached to the breech plug for sealinglyengaging against a primer opening of a cartridge case, the breech plugdefining a bore to allow a flame from an ignited primer to travel to aprojectile propellant at the breech end of the barrel; a substantiallycylindrical bolt aligned with the longitudinal axis without radiallyprojecting lugs, that is recipricatable and partially rotatable withinthe receiver between an open position in which the breech end of thebarrel is accessible for loading or removing the cartridge casing and aclosed position in which an end of the bolt can compressibly engageagainst the casing adjacent the primer cartridge, the bolt having acamming groove with a first section that extends longitudinally parallelto the axis and a second section that extends at an angle from arearward end of the first section; and a pin that extends through a wallof the receiver and engages the caroming groove to guide the bolt andlock the bolt against the primer at the face end of the ignition casingwhen it is loaded into the receiver, the camming groove and the metalpin configured to compress the face end of the ignition casing againstthe breech plug when the bolt is rotated into the closed position. 20.The muzzle loading firearm of claim 19, wherein the pin is threaded tofacilitate removal of the pin and from the receiver and for removal ofthe bolt from the receiver.
 21. The muzzle loading firearm of claim 19,wherein the breech plug includes external threads and the breech end ofthe barrel includes internal threads engagable with the external threadsof the breech plug.